How to reproduce:
1. Open the "timeout.zip" project
2. Add the "SampleScene" scene to build settings
3. Build the project for iOS
4. Build & Run the app to device via Xcode
5. Check the console

Actual result: Screen.sleepTimeout returns value of 15.
Expected result: Screen.sleepTimeout returns the value of "Auto-Lock" set at phone settings (in seconds).

Reproducible with: 2017.4.33f1, 2018.4.12f1, 2019.2.11f1, 2019.3.0b9, 2020.1.0a11.

Devices reproducible with:
- iPhone X (iOS 13.0)
- iPhone 6S (iOS 12.1.2)
- iPhone 7 (iOS 12.3.1)

Devices not reproducible with:
- VLNQA00257, Sony Xperia XZ Premium (G8141), Android 9, CPU: Snapdragon 835 MSM8998, GPU: Adreno (TM) 540